Powder-bonded forming apparatus and method for complex geological models

Abstract

The application discloses a powder bonding forming device and method for a complex geological model, which comprises a 3D printing control system, a material conveying tank, a powder falling and paving assembly, a forming box, an inkjet printing assembly, a rack, a forming box moving assembly, a longitudinal beam module and a powder cleaning assembly; the material conveying tank is fixed above the powder falling and paving assembly; the powder falling and paving assembly and the inkjet printing assembly are respectively fixed on longitudinal beam sliding rails of the longitudinal beam module through sliding blocks, and the two are separately moved without interfering with each other during printing and forming; the forming box is located directly below a rectangular space surrounded by the longitudinal beam module, and a forming platform is located in the forming box; the forming box moving assembly is arranged at the bottom of the forming box, and the forming box can be moved along a tow chain to realize moving in for printing and moving out for powder cleaning. The powder paving and bonding functions of the equipment are realized through different modules, the printing efficiency is improved, in addition, the forming platform is lifted from the side, the overall height of the equipment is greatly reduced, and stable vertical movement of the equipment is ensured.

Description

A powder bonding molding apparatus and method for complex geological models Technical Field

[0001] This invention relates to the fields of geotechnical engineering and mechanical engineering, specifically to a powder bonding molding apparatus and method for complex geological models. Background Technology

[0002] Geological structures containing numerous fracture networks severely impact the safety of major infrastructure and energy projects, threatening the safety of construction workers. Studying the disaster mechanisms and damage characteristics of complex geological models is fundamental to ensuring the safety of infrastructure and energy projects and guaranteeing the safety of construction personnel. Physical model testing is an important research method in geotechnical engineering; however, due to the presence of rock materials of varying strengths and complex fractures in complex geological structures, there are currently few mature methods for creating three-dimensional physical models of complex geological structures.

[0003] 3D printing is a technology that has emerged in recent years. It uses digital model files as a basis and employs mechanical automation technology to build three-dimensional objects by layering materials. Among them, powder bonding 3D printing technology is one of the most widely used technologies. The working principle of this technology is as follows: First, a layer of powder is laid on the printing platform. Then, according to the model information, adhesive is selectively sprayed onto specific locations of the powder layer to harden it. The above process is repeated to stack the layers to obtain the desired three-dimensional object, providing a new way for the fine molding of complex geological models. Application No. 201910255297.9 discloses a 3D printing device and a 3D printing method. The device includes a frame, a build platform, a powder spreading device, a printing device, and a motion device. The motion device simultaneously drives the powder spreading device and the printing device. However, this device is mainly designed for metal and plastic powders. Metal and plastic powders have good flowability. The powder in the powder spreading device falls automatically under its own weight, and no auxiliary powder falling device is set. It is not suitable for cement-based powders and cannot be used for the production of geological models. Moreover, the build platform is fixed below the printing device and cannot be removed after printing. The powder cleaning work can only be carried out inside the printing frame, which is inefficient. The liquid pump of this device draws liquid from the liquid tank and puts it into the filter unit through the pipeline. The filtered liquid is drawn by another liquid pump and supplied to the 3D printing device. It can be seen that its ink supply component is a pressure ink supply component and does not have the function of internal circulation ink supply in the nozzle, which is prone to nozzle clogging. Developing a powder-collecting and spreading system suitable for cement-based materials, a removable molding box, a side-wall lifting molding platform device, and a molding device integrating internal ink circulation supply in the printhead can improve the molding size and efficiency of complex geological models, reduce equipment height, and is of great significance for improving equipment stability and accuracy. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a complex geological model powder bonding molding device and method.

[0005] In a first aspect, the present invention provides a powder bonding molding device for complex geological models. The molding device includes a 3D printing control system 1, a material conveying tank 2, a powder feeding and spreading component 3, a molding box 4, an inkjet printing component 5, a frame 6, a molding box moving component 7, a longitudinal beam module 8, and a powder cleaning component 9. The 3D printing control system 1 is fixed on the frame 6 and is used to automatically control the powder bonding molding process.

[0006] The conveying tank 2 is fixed above the powder dispensing and spreading assembly 3, near one end of the powder dispensing and spreading assembly 3, and is used to draw external powder materials into the conveying tank and input them into the powder dispensing and spreading assembly 3 from the bottom outlet of the conveying tank.

[0007] The powder-spreading component 3 is fixed to the longitudinal beam slide rail of the longitudinal beam module 8 by a slider and moves freely along the longitudinal beam slide rail of the longitudinal beam module 8.

[0008] The inkjet printing component 5 is fixed to the longitudinal beam slide rail of the longitudinal beam module 8 by a slider, and moves freely along the longitudinal beam slide rail of the longitudinal beam module 8.

[0009] Both the powder-spreading component 3 and the inkjet printing component 5 can move along the longitudinal beam slide rail of the longitudinal beam module 8. During printing, the two can move independently without interfering with each other.

[0010] The molding box 4 is located directly below the rectangular space enclosed by the longitudinal beam module 8. The molding platform 42 is located inside the molding box 4. The powder falling and spreading component 3 spreads the powder material onto the molding platform 42. The three-dimensional model is stacked and formed by controlling the movement of the molding platform 42 along the Z-axis.

[0011] The frame 6 is generally rectangular, with the longitudinal beam modules fixed at the top of the frame and symmetrically arranged along the length of the frame. A space for placing the molding box is provided inside the frame.

[0012] A molding box moving assembly 7 is provided at the bottom of the molding box 4. The molding box moving assembly 7 includes a chassis frame 72 and a drag chain 71 welded to its upper part. The molding box 4 can move along the drag chain 71 to realize the molding box moving in for printing and moving out for powder cleaning.

[0013] The powder cleaning component 9 is located outside the molding device and is used to clean and recycle the powder removed from the molding box.

[0014] The powder-feeding and spreading assembly 3 includes a side fixing plate 32, a hopper 33, an auger 34, a powder-feeding plate 35, a vibration motor 36, a roller 37, a roller gear 38, and a conveyor belt 39. The two ends of the roller 37 are respectively connected to a side fixing plate 32 through bearings. The roller 37 is located below the side fixing plate. A No. 2 connecting plate 31 is fixedly connected to the top of the side fixing plate through an inclined plate. The No. 2 connecting plate 31 is fixed to the slider of the longitudinal beam module 8 by a No. 2 bolt 300, which drives the powder-feeding and spreading assembly 3 to move along the longitudinal beam slide rail of the longitudinal beam module.

[0015] A powder-feeding plate 35 is installed above the side fixing plate above the roller 37, and a material hopper 33 is fixedly installed between the two side fixing plates above the powder-feeding plate. One end of the roller 37 extends out of the side fixing plate and a roller gear 38 is installed. The roller gear 38 is located at one end of the roller 37 and outside the side fixing plate 32. The roller gear 38 is connected to the output end of a motor through a transmission belt 39. The motor drives the transmission belt, which in turn drives the roller gear 38 to rotate, ultimately controlling the rotation of the roller 37. After installation, the roller of the powder-feeding and spreading component 3 is located on the upper surface of the forming platform, and the roller 37 is behind the printing direction, thus compacting the powder material sprinkled on the surface of the forming platform. The powder-feeding and spreading component 3 extends into the forming box and can compact the material inside the forming box. The components above the No. 2 connecting plate 31 of the powder-feeding and spreading component 3 are fixed above the longitudinal beam module. During the printing process, the powder-feeding and spreading component does not move in the height direction.

[0016] The No. 1 discharge port 21 at the bottom of the conveying tank 2 is welded and fixed to the No. 1 connecting plate 22. The No. 1 connecting plate 22 is connected to the upper panel of the hopper 33 by the No. 1 bolt 220. The No. 1 discharge port 21 is directly opposite the open end of the hopper 33.

[0017] The auger 34 is located inside the hopper 33 and is connected to the hopper 33 by bearings. The hopper is long and narrow. Both the gear shaft and the auger are inside the hopper. The gear shaft is set at the outlet of the hopper. The auger is at the top of the hopper and the gear shaft is at the bottom of the hopper. A discharge port 302 is set below the gear shaft. The powder material is conveyed to one end of the hopper and accumulates. Under the action of the auger, the material is conveyed to the other end of the auger to fill the entire hopper. Then, the material falls to the powder drop plate 35 under the action of the gear shaft at the bottom of the hopper.

[0018] A No. 3 connecting plate 321 is installed on the inner wall of each of the two side fixing plates 32 between the hopper and the powder dropping plate. The No. 3 connecting plate 321 and the powder dropping plate 35 are connected together by a spring 322. A vibration motor 36 is set at the center of the upper surface of the powder dropping plate 35. The vibration motor 36 is fixed with bolts. The No. 3 connecting plate 321 is connected to the side fixing plate 32 with bolts. The powder dropping plate 35 vibrates slightly under the action of the vibration motor 36 and the spring 322. The powder material falling on the powder dropping plate 35 is evenly sprinkled onto the surface of the forming platform 42 under the action of vibration.

[0019] The mixing time for the auger to fill the entire hopper each time is controlled at 5-10 seconds, and the distance between the outer surface of the auger and the side wall of the hopper is 10-25 mm; the frequency of the vibration motor is controlled within the range of 30-50 Hz; the gear shaft 301 is provided with 6-8 grooves, and under the rotation of the gear shaft, the material enters the grooves and flows out, and the distance between the outer surface of the gear shaft and the side wall of the hopper outlet is 0.5-2 mm.

[0020] The molding box 4 includes side plates 40, reinforcing plates 41, bottom brackets 43, forklift slots 44, and lifting power components 45. The molding box contains four side plates 40 to form the maintenance structure of the molding box and restrict the movement of powder material in the horizontal direction. The reinforcing plates 41 are located on the two side plates 40 on the front and rear sides. The reinforcing plates 41 have a cross-sectional shape that is wider at the bottom and narrower at the top. A lifting power component 45 is provided on each of the left and right sides of the molding box to control the up and down movement of the molding platform 42. The molding platform is located inside the molding box, and the gap between the molding platform 42 and the side plates 40 is sealed with felt.

[0021] The lifting power assembly 45 includes a bracket 450, a lifting motor 451, a lifting screw 452, a lifting connector 453, a lifting slider 454, a lifting slide rail 455, and a lifting bracket 456. The lifting motor 451 is located at the bottom of the side plate 40, with its output end pointing vertically upward and connected to the lifting screw 452. Two lifting slide rails 455 are symmetrically installed on both sides of the lifting screw 452 via the bracket 450. The lifting slider 454 is installed on the lifting slide rail 455, and the lifting connector 453 is fixedly installed on the two lifting sliders 454. The center of the lifting connector 453 is fixed to the lifting screw 452. The lifting motor 451 drives the lifting screw 452 to rotate, thereby controlling the lifting connector 453 to move up and down along the lifting slide rail 455 as the screw 452 rotates.

[0022] The lifting bracket 456 is fixedly connected to the forming platform 42 by bolts. The two ends of the lifting bracket pass through the side plates of the forming box and are in contact connection with the lifting connecting member 453. On the left and right side plates 40, there are two slits each along the height direction. The connecting part between the lifting bracket and the forming platform can move up and down along the slits, providing a moving space for the lifting bracket 456. At this time, the two ends of the lifting bracket are located above the lifting connecting member and are in contact connection. When the lifting connecting member 453 rises, it can带动 the lifting bracket to rise. The two do not need to be welded and only need to be in contact. Lifting is achieved through contact, and when not in contact, the forming box can be horizontally moved;

[0023] A number of horizontal connecting members 457 fixedly connect the bracket 450 to the corresponding position of the frame 6;

[0024] The bottom bracket 43 of the forming box 4 can move along the drag chain 71 to achieve the in-move printing and out-move powder cleaning of the forming box. There is a forklift slot 44 at the bottom of the forming box. After the forming box is removed, a forklift forks into the forklift slot 44 to move the forming box away.

[0025] The inkjet printing component 5 described above includes an ink supply component 51, an inkjet connection plate 52, a crossbeam module 53, a nozzle fixing member 54, a nozzle fixing plate 57, and a nozzle 59;

[0026] The ink supply component 51 uses circulating negative pressure ink supply to continuously provide ink for the nozzle automatically;

[0027] The ink supply component 51 and the nozzle fixing member 54 are fixed to the inkjet connection plate 52 by bolts. The lower part of the nozzle fixing member 54 is installed with the nozzle fixing plate 57. The nozzle 59 is embedded in the nozzle fixing plate 57. The bottom surface of the nozzle is at the same horizontal plane as the bottom surface of the nozzle fixing plate 57. The nozzle extends into the forming box. The distance between the bottom surface of the nozzle and the surface of the forming platform is 3 - 6 mm. The nozzles are arranged in a "pin" shape in an array, and the overlap rate between the nozzles should be 1 - 3%. The nozzle fixing plate 57 is connected to the nozzle fixing member 54 by No. 3 bolts 58;

[0028] The middle part of the inkjet connection plate 52 is connected to the crossbeam module 53 through a slider. The ink supply component 51 and the nozzle 59 move horizontally along the horizontal slide rail 530 of the crossbeam module 53 under the action of the slider;

[0029] Both ends of the horizontal slide rail 530 are fixedly connected to the No. 4 connection plate 55 by bolts. The outside of the No. 4 connection plate 55 is fixed to the No. 5 connection plate 56. The No. 5 connection plate 56 is connected to the longitudinal beam module 8 through the corresponding slider.

[0030] The ink droplet size of the nozzle 59 is 15 - 80 pl.

[0031] Secondly, the present invention provides a powder bonding molding method for complex geological models, using the aforementioned molding apparatus, the molding method comprising the following steps:

[0032] (1) Establishing a mathematical model for the geological model;

[0033] (2) The geological model is sliced ​​using a slicing algorithm to obtain slice outline data;

[0034] (3) Convert the slice outline data of all layers into dot matrix data that can be read by the nozzle and transmit it to the 3D printing control system 1, and set the control software parameters for printing;

[0035] (4) The 3D printing control system 1 sends the data instruction of the layer to be printed to the nozzle to prepare for printing, and raises the forming platform to the highest position;

[0036] (5) Start printing and perform powder feeding and spreading: The feeding tank 2 sucks in the powder material and conveys it to the powder feeding and spreading component 3 through the outlet at its bottom. The powder is then fed and spread on the forming platform 42 from left to right. After one layer of powder is laid, the powder feeding and spreading component 3 returns to its original position to wait for instructions. The powder spreading speed is 20 to 50 seconds per layer. At the same time as the powder is spread, the 3D printing control system 1 sends the next layer data instruction to the nozzle.

[0037] (6) Perform inkjet printing: The inkjet printing component 5 prints in a stepping manner from right to left. The stepping width is the total effective spraying width of the array nozzles. When printing each step width, the nozzle 59 moves along the transverse slide rail of the beam module and sprays ink. Only the solid area of ​​the model is sprayed with ink to bond and solidify the powder material in the solid area. After completing one layer of inkjet printing, the inkjet printing component 5 returns to its original position to wait for instructions.

[0038] (7) Forming platform descent: The forming platform 42 of the forming box 4 moves downward by a layer thickness, the layer thickness being 0.1-0.3mm;

[0039] (8) Repeat steps (5) to (7) to print layer by layer to complete the model making;

[0040] (9) Use the molding box moving assembly 7 to move the molding box 4 out of the frame 6;

[0041] (10) Use the powder cleaning component 9 to clean and recycle the unconsolidated hardened powder in the molded box and take out the finished geological model.

[0042] The powder is a cement-based powder, mainly comprising cement and fine aggregates. The cement is one or more of ordinary silicate cement, sulfoaluminate cement, and magnesium phosphate cement. The ink used for inkjet printing is a water-based ink, which includes deionized water, viscosity modifier, solubilizer stabilizer, and surface tension modifier.

[0043] The molding method is used for printing adhesive 3D printing similar materials for complex geological models, the similar materials including powder materials and inks.

[0044] The powder material, by weight, comprises 10-40 parts of calcined MgO, 5-30 parts of phosphate, 30-100 parts of barite powder, 8-25 parts of hemihydrate gypsum, and 50-100 parts of precision-improving components.

[0045] The ink comprises 3-10% viscosity modifier, 0.5-2.5% solubilizer and stabilizer, 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% humectant, and 80-97% deionized water;

[0046] The viscosity modifier is at least one of PVA, polyvinylpyrrolidone (PVP), or xanthan gum;

[0047] The weight ratio of the ink to the powder material is 0.2-0.4; the precision improvement component includes PVA powder and cement clinker powder, and the mass ratio of the PVA powder to the cement clinker powder is 1:5-1:8.

[0048] The solubilizing stabilizer is at least one of 2-pyrrolidone and sodium pyrrolidone carboxylate.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] This invention provides a powder feeding and spreading component and a movable molding box for cement powder 3D printing. In order to improve printing efficiency, the printing part and the powder spreading part are separated. At the same time, it innovatively uses a high-precision printing nozzle and a circulating ink supply system.

[0051] (1) This invention achieves simultaneous printing of rock material and complex fracture structure by working together in steps such as powder laying, adhesive spraying and bonding molding and the movement of the molding platform, and by layer-by-layer stacking and bonding. The imported model has fracture structure inside, and the material used is rock material. By printing, rock material with fracture structure is formed, and a high-precision complex geological model is prepared, which solves the problem of making a three-dimensional physical model of complex geological structure.

[0052] (2) In view of the problem that cement-based powder is easy to agglomerate and has poor flowability, the present invention develops a vibrating powder dropping and spreading device, which can achieve uniform powder dropping and spreading of cement-based powder with low flowability.

[0053] (3) In view of the problem that the molding box of the existing powder printing equipment is fixed below the printing frame and the powder is difficult to clean, the present invention develops a movable molding box, which greatly improves the work efficiency; the removal of the molding box facilitates the removal of the model inside the box and the cleaning of the box.

[0054] (4) Existing powder printing equipment uses a pressure ink supply system, which does not have an internal ink circulation function in the printhead, which is prone to printhead clogging. The printhead of this invention is a circulating ink supply component, which can realize the continuous circulation of ink inside the printhead and avoid printhead clogging caused by ink sedimentation.

[0055] (5) In view of the problem that the existing equipment controls the lifting and lowering of the molding platform from the bottom, resulting in a large equipment height, the side wall of the molding box of the present invention is equipped with a lifting power component, which reduces the height of the equipment by half and greatly improves the stability of the equipment operation.

[0056] This invention overcomes the problem in existing technologies where the amount of powder produced in a single print is limited by the size of the powder supply cylinder, thus restricting the size of the model. This invention reduces the limitation on powder addition by increasing the powder hopper capacity. (Traditional 3D printers use a dual-cylinder powder supply mechanism, containing two cylinders: one for supplying powder (the powder supply cylinder) and the other for providing the printing workspace (the printing cylinder). First, the powder supply cylinder is filled with material. Then, the cylinder platform is raised, pushing the material above the printing plane. A spreading shaft then spreads the material onto the printing cylinder platform for printing. The main problem with this mechanism is that the maximum print size is limited by the powder supply cylinder capacity. This invention uses a waterfall-style powder delivery mechanism, allowing material to be continuously fed to the hopper, so the size of the printed model is not limited by the size of the molding hopper.) Furthermore, this invention is suitable for printing cement powder and can be used to simulate the brittleness of geological model materials.

[0057] In this invention, the powder spreading and bonding functions of the equipment are implemented through different modules, which improves printing efficiency. In addition, by lifting the forming platform from the side, the overall height of the equipment is greatly reduced, ensuring the stable vertical movement of the equipment. Attached Figure Description

[0058] Figure 1 is a schematic diagram of the overall structure of a powder bonding molding device for a complex geological model according to an embodiment of the present invention.

[0059] Figure 2 is a schematic diagram of the structure of a powder-feeding and powder-spreading component according to an embodiment of the present invention;

[0060] Figure 3 is a schematic diagram of the structure of a molding box according to an embodiment of the present invention;

[0061] Figure 4(a) is a schematic diagram of the structure of an inkjet printing assembly according to an embodiment of the present invention;

[0062] Figure 4(b) is a schematic diagram of the lower part of the printhead fixing member 54 in an inkjet printing assembly according to an embodiment of the present invention;

[0063] Figure 5 is a schematic diagram of the structure of a powder cleaning component according to an embodiment of the present invention;

[0064] In the diagram: 1. 3D printing control system; 2. Feed tank; 3. Powder feeding and spreading assembly; 4. Molding box; 5. Inkjet printing assembly; 6. Frame; 7. Molding box moving assembly; 8. Longitudinal beam module; 9. Powder cleaning assembly; 42. Molding platform; 71. Chassis frame; 72. Cable chain; 21. No. 1 discharge port; 22. No. 1 connecting plate; 220. No. 1 bolt; 31. No. 2 connecting plate; 300. No. 2 bolt; 32. Side fixing plate; 33. Hopper; 34. Screwdriver; 35. Powder feeding plate; 36. Vibration motor; 37. Roller; 38. Roller gear; 39. Conveyor belt; 301. Gear shaft; 302. No. 2 discharge port; 322. Spring; 321. 40. Connecting plate No. 3, 41. Side plate, 42. Reinforcing plate, 43. Bottom bracket, 44. Forklift slot, 45. Lifting power assembly, 450. Bracket, 451. Lifting motor, 452. Lifting screw, 453. Lifting connector, 454. Lifting slider, 455. Lifting slide rail, 456. Lifting bracket, 457. Horizontal connector, 51. Ink supply assembly, 52. Inkjet connecting plate, 53. Crossbeam module, 54. Printhead fixing component, 55. Connecting plate No. 4, 56. Connecting plate No. 5, 57. Printhead fixing plate, 58. Bolt No. 3, 59. Printhead, 530. Horizontal slide rail, 91. Dust collection power unit, 92. Dust suction pipe, 93. Recovery pipe. Detailed Implementation

[0065] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention and do not limit the scope of protection of the claims of this application.

[0066] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0067] The present invention provides a powder bonding molding device for complex geological models (see Figures 1-5). The device includes a 3D printing control system 1, a material conveying tank 2, a powder spreading component 3, a molding box 4, an inkjet printing component 5, a frame 6, a molding box moving component 7, a longitudinal beam module 8, and a powder cleaning component 9.

[0068] The 3D printing control system 1 is fixed on the frame 6 and located in the upper right of the entire device for easy manual operation. It is used to automatically control the powder bonding and molding process.

[0069] The conveying tank 2 is fixed above the powder dispensing and spreading assembly 3, near one end of the powder dispensing and spreading assembly 3, and is used to draw external powder materials into the conveying tank and input them into the powder dispensing and spreading assembly 3 from the bottom outlet of the conveying tank.

[0070] The powder-spreading component 3 is fixed to the longitudinal beam slide rail of the longitudinal beam module 8 by a slider, and can move freely along the longitudinal beam slide rail of the longitudinal beam module 8.

[0071] The inkjet printing component 5 is fixed to the longitudinal beam slide rail of the longitudinal beam module 8 by a slider, and can move freely along the longitudinal beam slide rail of the longitudinal beam module 8.

[0072] Both the powder-feeding and powder-spreading component 3 and the inkjet printing component 5 can move along the longitudinal beam slide rail of the longitudinal beam module 8. During printing, the two can move independently without interfering with each other.

[0073] The molding box 4 is located directly below the rectangular space enclosed by the longitudinal beam module 8. The molding platform 42 is located inside the molding box 4. The powder falling and spreading component 3 spreads the powder material onto the molding platform 42. The three-dimensional model is stacked and formed by controlling the movement of the molding platform 42 along the Z-axis.

[0074] The frame 6 is generally rectangular, with the longitudinal beam modules fixed at the top of the frame and symmetrically arranged along the length of the frame. A space for placing the molding box is provided inside the frame. The longitudinal beam modules 8 are welded and fixed to the frame 6, limiting the range of movement of the longitudinal beam modules 8.

[0075] A molding box moving assembly 7 is provided at the bottom of the molding box 4. The molding box moving assembly 7 consists of a chassis frame 72 and a drag chain 71 welded to its upper part. The molding box 4 can move along the drag chain 71 to realize the molding box moving in for printing and moving out for powder cleaning.

[0076] The powder cleaning component 9 is located outside the molding device and is used to clean and recycle the powder removed from the molding box, making it easier to remove the model.

[0077] The powder-feeding and spreading assembly 3 adopts an upper waterfall-type powder-feeding mechanism, including a side fixing plate 32, a hopper 33, an auger 34, a powder-feeding plate 35, a vibration motor 36, a roller 37, a roller gear 38, and a conveyor belt 39. Both ends of the roller 37 are connected to a side fixing plate 32 via bearings. The roller 37 is located below the side fixing plate. A second connecting plate 31 is fixedly connected to the top of the side fixing plate via an inclined plate. The second connecting plate 31 is fixed to the slider of the longitudinal beam module 8 by bolts 300, driving the powder-feeding and spreading assembly 3 to move along the longitudinal beam slide rail of the longitudinal beam module.

[0078] A powder-feeding plate 35 is installed above the side fixing plate above the roller 37, and a material hopper 33 is fixedly installed between the two side fixing plates above the powder-feeding plate. One end of the roller 37 extends out of the side fixing plate and is fitted with a roller gear 38. The roller gear 38 is located at one end of the roller 37 and outside the side fixing plate 32. The roller gear 38 is connected to the output end of a motor via a transmission belt 39. The motor drives the transmission belt, which in turn drives the roller gear 38 to rotate, ultimately controlling the rotation of the roller 37. After installation, the roller of the powder-feeding and spreading component 3 is located on the upper surface of the forming platform, and the roller 37 is behind the printing travel direction, thus compacting the powder material sprinkled on the surface of the forming platform. The powder-feeding and spreading component 3 extends into the forming box to compact the material inside the forming box. The components above the No. 2 connecting plate 31 of the powder-feeding and spreading component 3 are fixed above the longitudinal beam module. The model height is stacked by the lowering of the forming platform inside the forming box. During the printing process, the powder spreading component does not move in the height direction.

[0079] The No. 1 discharge port 21 at the bottom of the conveying tank 2 is welded and fixed to the No. 1 connecting plate 22. The No. 1 connecting plate 22 is connected to the upper panel of the hopper 33 by the No. 1 bolt 220. The No. 1 discharge port 21 is directly opposite the open end of the hopper 33.

[0080] The auger 34 is located inside the hopper 33 and is connected to the hopper 33 via a bearing. The powder material flows into the hopper 33 through the No. 1 outlet 21 of the conveying tank and is filled into the entire hopper 33 by the rotation of the auger 34. According to the test, the stirring time of the auger each time should be controlled within 5-10 seconds. If the time is too short, the powder material cannot be completely filled into the hopper. If the time is too long, the powder material will be compacted, which is not conducive to the powder falling off.

[0081] The hopper 33 has a No. 2 discharge port 302 at its bottom, and a continuous gear shaft 301 is provided along the length of the bottom of the hopper. The powder material inside the hopper 33 is precisely extruded from the No. 2 discharge port 302 at the bottom of the hopper under the rotation of the gear shaft 301. The extruded powder material falls onto the powder drop plate 35 under gravity. The hopper is elongated, with both the gear shaft and the auger inside. The auger is at the top of the hopper, and the gear shaft is at the bottom. The powder material is conveyed to one end of the hopper and accumulates. Under the action of the auger, the material is conveyed to the other end of the auger, filling the entire hopper. Then, the material falls onto the powder drop plate under the rotation of the gear shaft at the bottom of the hopper.

[0082] A No. 3 connecting plate 321 is installed on the inner wall of each of the two side fixing plates 32 between the hopper and the powder dropping plate. The No. 3 connecting plate 321 and the powder dropping plate 35 are connected together by a spring 322. A vibration motor 36 is set at the center of the upper surface of the powder dropping plate 35. The vibration motor 36 is fixed with bolts, and the No. 3 connecting plate 321 is connected to the side fixing plate 32 with bolts. The powder dropping plate 35 vibrates slightly under the action of the vibration motor 36 and the spring 322. The powder material falling on the powder dropping plate 35 is evenly sprinkled onto the surface of the forming platform 42 under the action of vibration. In order to ensure the uniformity of powder falling and reduce the impact of vibration on operation, the frequency of the vibration motor should be in the range of 30-50Hz.

[0083] The molding box 4 includes side plates 40, reinforcing plates 41, a bottom support 43, a forklift slot 44, and a lifting power assembly 45. The molding box contains four side plates 40, forming a protective structure that restricts the horizontal movement of the powder material. The reinforcing plates 41 are designed with a cross-sectional shape that is wider at the bottom and narrower at the top, providing stable horizontal support for the side plates 40. A lifting power assembly 45 is located on each of the left and right sides of the molding box to control the vertical movement of the molding platform 42. The molding platform is located inside the molding box, and the gap between the molding platform 42 and the side plates 40 is sealed with felt to prevent powder material from leaking into the molding platform.

[0084] The reinforcing plate is located on the two side plates 40 on the front and rear sides. In this invention, the direction in which the molding box is pulled closer and pulled out is defined as the front and rear direction. The orientation relationship is described using the state in Figure 1 as an example.

[0085] The lifting power assembly 45 consists of a bracket 450, a lifting motor 451, a lifting screw 452, a lifting connector 453, a lifting slider 454, a lifting slide rail 455, and a lifting bracket 456. The lifting motor 451 is located at the bottom of the side plate 40, with its output end pointing vertically upward and connected to the lifting screw 452. Two lifting slide rails 455 are symmetrically installed on both sides of the lifting screw 452 via the bracket 450. Lifting sliders 454 are installed on the lifting slide rails 455, and lifting connectors 453 are fixedly installed on the two lifting sliders 454. The center of the lifting connector 453 is fixed to the lifting screw 452. The lifting motor 451 drives the lifting screw 452 to rotate, thereby controlling the lifting connector 453 to move up and down along the lifting slide rail 455 as the screw 452 rotates.

[0086] The lifting bracket 456 is fixedly connected to the forming platform 42 by bolts. Both ends of the lifting bracket protrude from the side plates of the forming box and contact the lifting connector 453. Two slots are provided on each of the left and right side plates 40 along the height direction. The connection between the lifting bracket and the forming platform can move up and down along the slots, providing space for the lifting bracket 456 to move. At this time, both ends of the lifting bracket are located above the lifting connector, and the two are in contact. When the lifting connector 453 rises, it can drive the lifting bracket to rise. The two do not need to be welded; contact is sufficient for lifting. When not in contact, the forming box can be moved horizontally.

[0087] Several horizontal connectors 457 fix the bracket 450 to the frame 6 at the corresponding position, thereby connecting the lifting power assembly 45 to the frame 6 together;

[0088] The bottom support 43 of the molding box 4 can move along the cable chain 71 to realize the printing and powder removal of the molding box. The bottom of the molding box is provided with a forklift slot 44. After the molding box is removed, the forklift can fork into the forklift slot 44 to remove the molding box.

[0089] The lifting motor 451 controls the up-and-down movement of the lifting connector 453, which in turn controls the up-and-down movement of the lifting bracket 456, and in turn controls the up-and-down movement of the forming platform.

[0090] The inkjet printing assembly 5 consists of an ink supply assembly 51, an inkjet connecting plate 52, a crossbeam module 53, a printhead fixing component 54, a printhead fixing plate 57, and a printhead 59.

[0091] The ink supply component 51 preferably uses a circulating negative pressure ink supply system to automatically and continuously supply ink to the printhead. The circulating negative pressure ink supply component can realize the self-circulation of ink during the printing process, reduce air bubbles in the ink, and improve the phenomenon of ink sedimentation clogging the nozzle.

[0092] The ink supply component 51 and the nozzle fixing part 54 are fixed to the inkjet connection plate 52 by bolts. The lower part of the nozzle fixing part 54 is equipped with a nozzle fixing plate 57. The nozzle 59 is embedded in the nozzle fixing plate 57. The bottom surface of the nozzle is at the same horizontal plane as the bottom surface of the nozzle fixing plate 57. The nozzle extends into the forming box. The distance between the bottom surface of the nozzle and the surface of the forming platform should be 3 - 6 mm. An array of nozzles is arranged in a "pin" shape, and the overlap rate between nozzles should be 1 - 3%. The nozzle fixing plate 57 is connected to the nozzle fixing part 54 by bolt No. 3 58.

[0093] To meet the requirements of forming accuracy, the ink droplet size of the nozzle 59 should be 15 - 80 pl. The middle part of the inkjet connection plate 52 is connected to the crossbeam module 53 through a slider. The ink supply component 51 and the nozzle 59 can move horizontally along the horizontal slide rail 530 of the crossbeam module 53 under the action of the slider. The two ends of the horizontal slide rail 530 of the inkjet printing component 5 are respectively fixedly connected to the No. 4 connection plate 55 by bolts. The outside of the No. 4 connection plate 55 is fixed to the No. 5 connection plate 56. The No. 5 connection plate 56 is connected to the longitudinal beam module 8 through a corresponding slider and can move freely along the longitudinal beam slide rail of the longitudinal beam module 8.

[0094] The forming box moving component 7 consists of a chassis frame 72 and a drag chain 71 welded to its upper part. The chassis frame is located at the bottom of the forming box. A drag chain 71 in the front - rear direction is arranged on the chassis frame. The bottom bracket 43 of the forming box cooperates with the drag chain, enabling the forming box to move out of the printing area along the drag chain. The bottom bracket of the forming box can move along the drag chain to realize the movement of the forming box into the printing area and out for powder cleaning. There is a forklift slot at the bottom of the forming box. After the forming box is removed, a forklift can be inserted into the forklift slot to move the forming box away.

[0095] The powder cleaning component 9 includes a dust suction power device 91, a powder suction pipe92, and a recovery pipe 93. The powder suction pipe 92 is placed inside the forming box 4. The dust suction power device 91 sucks the unbonded and uncured powder material through the powder suction pipe 92 into the dust suction power device 91. A recovery pipe 93 is fixed to the end of the dust suction power device 91. The recovery pipe 93 is connected to the material bin 33. The powder material sucked into the dust suction power device 91 enters the material bin 33 through the recovery pipe 93 for recycling.

[0096] Preferably, the powder - dropping and powder - spreading component 3, the forming box 4, and the inkjet printing component 5 have the characteristic of independent operation. When the powder - dropping and powder - spreading component 3 is in the state of adding powder, the inkjet printing component 5 can still work, improving the work efficiency. The forming box can work independently. It should be noted that the so - called independent operation here means that the box body can be controlled to move separately by the system and can be moved out for powder cleaning after printing.

[0097] The mixing time for the auger to fill the entire hopper each time is controlled at 5-10 seconds, and the distance between the outer surface of the auger and the side wall of the hopper is 10-25 mm; the frequency of the vibration motor is controlled within the range of 30-50 Hz; the gear shaft 301 is provided with 6-8 grooves, and under the rotation of the gear shaft, the material enters the grooves and flows out, and the distance between the outer surface of the gear shaft and the side wall of the hopper outlet is 0.5-2 mm.

[0098] This invention also provides a powder bonding molding method for complex geological models, the method comprising the following steps:

[0099] (11) Establish a mathematical model for the geological model;

[0100] (12) The geological model is sliced ​​using a slicing algorithm to obtain slice outline data;

[0101] (13) Convert the slice outline data of all layers into dot matrix data that can be read by the nozzle and transmit it to the 3D printing control system 1, and set the control software parameters for printing;

[0102] (14) The 3D printing control system 1 sends the data instruction of the layer to be printed to the nozzle to prepare for printing, and raises the forming platform to the highest position;

[0103] (15) Start printing and begin powder application: The feed tank 2 draws in the powder material and delivers it through the outlet at its bottom to the powder application assembly 3. The powder is then applied and rolled from left to right on the forming platform 42. After one layer of powder is applied, the powder application assembly 3 returns to its original position to await further instructions. The powder application speed should be 20–50 seconds per layer. Simultaneously, the 3D printing control system 1 sends the next layer data instruction to the nozzle.

[0104] (16) Perform inkjet printing: The inkjet printing component 5 prints in a stepping manner from right to left. The stepping width is the total effective spraying width of the array of printheads. When printing each step width, the printhead 59 moves along the transverse slide rail of the beam module and sprays ink. Only the solid area of ​​the model is sprayed with ink to bond and solidify the powder material in the solid area. After completing one layer of inkjet printing, the inkjet printing component 5 returns to its original position to wait for instructions.

[0105] (17) Forming platform descent: The forming platform 42 of the forming box 4 moves downward by a layer thickness under the action of the lifting power device 45. The layer thickness should be 0.1-0.3mm.

[0106] (18) Repeat steps (5) to (7) to print layer by layer to complete the model making;

[0107] (19) The molding box 4 is moved out of the frame 6 using the molding box moving assembly 7;

[0108] (20) Use the powder cleaning component 9 to clean and recycle the unconsolidated hardened powder in the molded box and take out the finished geological model.

[0109] The powder described in this invention is a cement-based powder, mainly comprising cement and fine aggregates. The cement is one or more of ordinary silicate cement, sulfoaluminate cement, and magnesium phosphate cement. The ink used for inkjet printing is a water-based ink, which includes deionized water, viscosity modifier, solubilizer stabilizer, and surface tension modifier.

[0110] Example 1

[0111] This embodiment uses the above-described molding apparatus to print adhesive 3D printing similar materials for complex geological models. The similar materials include powder materials and ink.

[0112] The powder material, by weight, comprises 10-40 parts of calcined MgO, 5-30 parts of phosphate, 30-100 parts of barite powder, 8-25 parts of hemihydrate gypsum, and 50-100 parts of precision-improving components.

[0113] The ink comprises 3-10% viscosity modifier, 0.5-2.5% solubilizer and stabilizer, 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% humectant, and 80-97% deionized water;

[0114] The viscosity modifier is at least one of PVA, polyvinylpyrrolidone (PVP), or xanthan gum;

[0115] The weight ratio of the ink to the powder material is 0.2-0.4; the precision improvement component includes PVA powder and cement clinker powder, and the mass ratio of the PVA powder to the cement clinker powder is 1:5-1:8.

[0116] The solubilizing stabilizer is at least one of 2-pyrrolidone and sodium pyrrolidone carboxylate.

[0117] The surface tension modifier is a nonionic surfactant, the defoamer is an organosilicon defoamer with a pH of 3-14, and the humectant is at least one of glycerin and 1,2-propanediol.

[0118] The ink has a viscosity of 3-15 mPa·s and a surface tension of 35-55 mN / m.

[0119] The PVA powder is one or more of the following types: 17-80, 17-88, 17-92, and K30, with a purity greater than 98%, a molecular weight of 30,000 to 100,000, and a fineness of 150 to 200 mesh; the cement clinker powder is one or more of the following: ordinary silicate cement clinker, sulfoaluminate cement clinker, and aluminate cement clinker, with a particle size of 0.045 to 0.125 mm.

[0120] The density of the hemihydrate gypsum is 2.6 g / cm³. 3 The purity is greater than 98%, and the particle size ranges from 0.075 to 0.125 mm; the bulk density of the barite powder is 3.2-3.8 g / cm³. 3 The particle size range is 0.075-0.15 mm;

[0121] The recalcined MgO is obtained by calcining MgO material in a high-temperature furnace at 1600–1950℃ for 50–120 min, followed by ball milling at 1500–1800 r / min for 15–35 min and then sieving. Its bulk density is 1.8–2.0 g / cm³. 3 Specific surface area is 230-287 m² 2 / kg, with a particle size range of 0.075-0.15mm;

[0122] The phosphate is one or more of potassium dihydrogen phosphate, ammonium dihydrogen phosphate and sodium dihydrogen phosphate powder, and the purity of the phosphate material is above 92% and the maximum particle size is 0.125 mm.

[0123] The preparation method of similar materials includes the following steps:

[0124] (1) Add 10-40 parts of calcined MgO, 5-30 parts of phosphate and 30-100 parts of barite powder to a planetary mixer and stir for 5-10 minutes until the mixture is uniform; then add 8-25 parts of hemihydrate gypsum and 50-100 parts of precision improvement component, and continue stirring for 10-15 minutes until the mixture is uniform to obtain the powder material.

[0125] (2) Add 3-10% viscosity modifier to 0.5-2.5% solubilizer and stabilizer, and stir for 10-15 minutes until the mixture is uniform;

[0126] (3) Add 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% humectant, and 80-97% deionized water to the above solution and ultrasonically disperse for 5-10 minutes using an ultrasonic disperser at a frequency of 50 Hz.

[0127] (4) The ink was vacuum filtered sequentially using PP material filter membranes of 15μm, 10μm and 0.5μm, with a filtration negative pressure of 0.7-0.8MPa;

[0128] (5) The filtered ink is degassed in sequence using a vacuum degassing tank and a vacuum degassing mold to obtain the ink material;

[0129] (6) Add the powder material prepared above to the feeding tank 2, add the ink material to the ink supply assembly, and print using powder 3D printing technology. The layer thickness is 0.1-0.2 mm, and the printing speed is 600-800 mm / s. After printing, remove the unbonded powder, take out the model, place it in the curing film, and cure it indoors for 24 hours to obtain a complex geological model that meets the test requirements.

[0130] The tests show that the similar material in this embodiment is a high-density and highly brittle material, with a density of 2.4 g / cm³. 3 The tensile strength to compressive strength ratio is above 15, exhibiting brittleness similar to that of rock. While achieving 3D printing, the similarity to the rock model is ensured, and its material strength, elastic modulus, density, and brittleness all meet the similarity requirements.

[0131] In this embodiment, hemihydrate gypsum and barite powder are added as auxiliary components to the magnesium phosphate component in the powder material, and a precision-improving component containing cement clinker powder is added. A high ink usage (the weight ratio of ink to powder material is 0.2-0.4, while the conventional ink usage is generally controlled at a weight ratio of ink to powder material not greater than 0.1) is used to achieve high homogeneity, high brittleness, high density and high precision at low strength.

[0132] In this embodiment, the precision-improving component consists of highly water-soluble PVA powder and cement clinker powder. PVA powder prevents excessive ink diffusion in the powder material, improving molding precision. Appropriate amounts of cement clinker powder react with MgO and phosphate, significantly mitigating the shrinkage and cracking problems caused by rapid reaction of MgO and phosphate under high ink volume. Furthermore, it controls the setting time to within 1 minute, achieving rapid setting without significantly increasing strength, thus improving ink diffusion and further enhancing the material's molding precision. In this embodiment, the recalcined MgO, phosphate, barite powder, hemihydrate gypsum, and precision-improving component, due to their specific formulation and particle size distribution, do not agglomerate during powder printing, exhibiting good fluidity. The barite powder is processed using a circular grinding process, resulting in rounded polygonal particles, all of which contribute to improving the spreading and packing density of the powder material.

[0133] Using the molding device and printing material of this invention, the ink has the characteristics of not clogging the nozzle, not continuously spraying, not burning the nozzle, not deteriorating, not atomizing, and high-precision printing, which meets the requirements of powder 3D printing and obtains similar material models with better accuracy.

[0134] Example 2

[0135] (1) Add 30 parts of recalcined MgO, 15 parts of ammonium dihydrogen phosphate, and 80 parts of barite powder to a planetary mixer and stir for 10 minutes until uniformly mixed. Then, add 20 parts of hemihydrate gypsum and 90 parts of the precision-improving component, and continue stirring for 10 minutes until uniformly mixed to obtain the powder material. The recalcined MgO is obtained by calcining MgO material in a high-temperature furnace at 1700℃ for 120 minutes, followed by ball milling at 1600 r / min for 30 minutes and sieving. Its bulk density is 1.8 g / cm³. 3 Specific surface area is 252m² 2 / kg, particle size range 0.075-0.15mm; ammonium dihydrogen phosphate purity 96%, maximum particle size 0.125mm; barite powder particles are rounded polygons, bulk density 3.5g / cm3, particle size range 0.075-0.15mm. Hemihydrate gypsum density is 2.6g / cm3. 3 The purity is greater than 98%, and the particle size range is 0.075-0.125mm. The precision improvement component includes 15 parts PVA powder and 75 parts sulfoaluminate cement clinker powder; the PVA powder is K30 type, with a purity of 98% and a fineness of 200 mesh; the sulfoaluminate cement clinker particle size is 0.045-0.125mm.

[0136] (2) Add 8% PVA to 1.2% 2-pyrrolidone and stir for 10 minutes until the mixture is homogeneous;

[0137] (3) Add 0.5% nonionic surfactant Surfynol 465, 0.05% silicone defoamer, 4% 1,2-propanediol, and 90% deionized water to the above solution and ultrasonically disperse for 8 min using an ultrasonic disperser at a frequency of 50 Hz; the effective ingredient content of Surfynol 465 is greater than 99%; the effective ingredient content of silicone defoamer is greater than 98%, and the pH is 3-14;

[0138] (4) The ink was vacuum filtered sequentially using PP material filter membranes of 15μm, 10μm and 0.5μm, with a filtration negative pressure of 0.7MPa;

[0139] (5) The filtered ink is degassed in sequence using a vacuum degassing tank and a vacuum degassing mold to obtain the ink material;

[0140] The prepared powder material is added to the printer's feed tank, and the ink material is added to the ink supply assembly. The weight ratio of ink to powder material is 0.3:1. Powder 3D printing is performed with a layer thickness of 0.15 mm and a printing speed of 600 mm / s. After printing, the unbonded powder is removed, the model is taken out, and placed in a curing film. After curing indoors for 24 hours, a complex geological model that meets the experimental requirements can be obtained.

[0141] Using this embodiment, a 3D printed structure was obtained. The printing process proceeded smoothly without cracking, and the printed structure exhibited good integrity and precision. The geometric scale of the model compared to the prototype is commonly 1:50 or 1:25, while the density and Poisson's ratio are typically measured at a scale of 1:1. Therefore, the compressive strength and elastic modulus scales are 1:50 or 1:25. As shown in Table 1, the structure exhibits obvious brittle failure compared to rock mechanical and physical properties. This indicates that this material is suitable for simulating the mechanical properties of hard rock materials at a 1:50 scale.

[0142] Example 3

[0143] Compared with Example 2, this embodiment differs in that 30 parts of recalcined MgO and 15 parts of ammonium dihydrogen phosphate are changed to "15 parts of recalcined MgO and 15 parts of ammonium dihydrogen phosphate," and 80 parts of barite powder are changed to 90 parts of barite powder. The mass ratio of ink to powder material is 0.25:1, and the 90 parts of the precision-improving component include 10 parts of PVA powder and 80 parts of sulfoaluminate cement clinker powder. Using this embodiment, a printed structure was obtained. The printing process proceeded smoothly, and the printed structure exhibited good integrity and precision, with significant brittle fracture. The printing precision was good, with a minimum printable precision of 0.16 mm. Using this embodiment, a 3D printed structure was obtained. The printing process proceeded smoothly without cracking, and the printed structure exhibited good integrity and precision. A comparison with rock mechanical and physical properties is shown in Table 2, indicating that the structure showed significant brittle fracture. This demonstrates that this material is suitable for simulating the mechanical properties of soft rock materials at a 1:50 scale.

[0144] Table 1

[0145]

[0146] Table 2

[0147]

[0148] Traditional powder 3D printing typically uses materials like plaster and sand, which have good flowability and can fall automatically under gravity. The molding device of this invention is particularly suitable for cement-based materials. Cement materials have sharp edges, are prone to agglomeration, and have poor flowability. In traditional methods, an auger is installed in the hopper, with the distance between the auger's outer surface and the hopper sidewall set at 10-25mm. When the distance is too large, the auger struggles to agitate the material on the hopper sidewall, resulting in voids at the auger and difficulty in material discharge. When the distance is too small, the rotation of the auger compresses the lower material, making it difficult to flow to the outlet. This invention incorporates a gear shaft at the hopper outlet, enabling precise control of the powder discharge. The gear shaft preferably has 6-8 grooves, allowing material to enter and flow out under the rotation of the gear shaft. The distance between the outer surface of the gear shaft and the side wall of the hopper outlet is 0.5-2mm. If the distance is too small, the powder cannot enter the groove of the gear shaft under the action of the gear shaft rotation. If the distance is too large, some powder will flow away in the gap between the gear shaft and the side wall of the outlet, and the amount of powder falling is difficult to control precisely.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0150] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A powder bonding and molding device for complex geological models, characterized in that, This molding device is suitable for cement-based materials, which have sharp edges, are prone to agglomeration, and have poor flowability. It includes a 3D printing control system, a feeding tank, a powder spreading assembly, a molding box, an inkjet printing assembly, a frame, a molding box moving assembly, a longitudinal beam module, and a powder cleaning assembly. The 3D printing control system is fixed to the frame and is used to automatically control the powder bonding and molding process. The feeding tank is fixed above the powder spreading assembly, near one end of the assembly, and is used to draw external powder material into the tank and input it into the powder spreading assembly from the bottom outlet of the tank. The powder spreading assembly is fixed to the longitudinal beam slide rail of the longitudinal beam module by a slider and moves freely along the longitudinal beam slide rail. The inkjet printing assembly is fixed by a slider. The component moves freely along the longitudinal beam slide rail of the longitudinal beam module. Both the powder-feeding and powder-spreading assembly and the inkjet printing assembly can move along the longitudinal beam slide rail of the longitudinal beam module. During printing, their individual movements do not interfere with each other. The forming box is located directly below the rectangular space enclosed by the longitudinal beam modules. The forming platform is located inside the forming box. The powder-feeding and powder-spreading assembly spreads powder material onto the forming platform, and the 3D model is stacked and formed by controlling the movement of the forming platform along the Z-axis. The frame is generally rectangular, with the longitudinal beam modules fixed to the upper end of the frame and symmetrically arranged along the length of the frame. A space for placing the forming box is provided inside the frame. A forming box moving assembly is located at the bottom of the forming box, comprising a chassis frame and welded components. The upper part of the cable chain allows the forming box to move along the cable chain, enabling the forming box to be moved in for printing and removed for powder cleaning. The powder cleaning component is located outside the forming device and is used to clean and recycle the powder removed from the forming box. The powder dispensing and spreading component includes a side fixing plate, a hopper, an auger, a powder dispensing plate, a vibration motor, a roller, roller gears, and a conveyor belt. Both ends of the roller are connected to a side fixing plate via bearings. The roller is located below the side fixing plate. A No. 2 connecting plate is fixedly connected to the top of the side fixing plate via an inclined plate. The No. 2 connecting plate is fixed to the slider of the longitudinal beam module with a No. 2 bolt, driving the powder dispensing and spreading component to move along the longitudinal beam slide rail of the longitudinal beam module. A powder dispensing plate is installed above the side fixing plate above the roller. Above the powder dispensing plate... A material hopper is fixedly installed between two side fixing plates; one end of the roller extends out of the side fixing plate and a roller gear is installed. The roller gear is located at one end of the roller and outside the side fixing plate. The roller gear is connected to the output end of a motor through a transmission belt. The motor drives the transmission belt, which in turn drives the roller gear to rotate, ultimately controlling the rotation of the roller. After installation, the roller of the powder-feeding and spreading component is located on the upper surface of the forming platform. The roller is behind the printing travel direction, thus compacting the powder material sprinkled on the surface of the forming platform. The powder-feeding and spreading component extends into the forming box and can compact the material inside the forming box. The components above the No. 2 connecting plate of the powder-feeding and spreading component are fixed above the longitudinal beam module. During the printing process, the powder-feeding and spreading component does not move in the height direction.The No. 1 discharge port at the bottom of the conveying tank is welded and fixed to the No. 1 connecting plate. The No. 1 connecting plate is connected to the upper panel of the hopper using the No. 1 bolt. The No. 1 discharge port faces the open end of the hopper. The auger is located inside the hopper and is connected to the hopper via bearings. The hopper is elongated, with both the gear shaft and the auger inside. The gear shaft is located at the hopper outlet, the auger is at the top of the hopper, and the gear shaft is at the bottom of the hopper. The No. 2 discharge port is located below the gear shaft. Powdered material is conveyed to one end of the hopper and accumulates. Under the action of the auger, the material is conveyed to the other end of the auger, thus filling the hopper. The entire hopper is then filled with material, which falls onto the powder-dropping plate under the action of the gear shaft at the bottom of the hopper. Connecting plates No. 3 are installed on the inner walls of the two side fixing plates between the hopper and the powder-dropping plate, and these connecting plates are connected to the powder-dropping plate by springs. A vibration motor is installed at the center of the upper surface of the powder-dropping plate, and the vibration motor is fixed with bolts. Connecting plates No. 3 are connected to the side fixing plates with bolts. The powder-dropping plate vibrates slightly under the action of the vibration motor and springs, and the powder material falling onto the powder-dropping plate is evenly sprinkled onto the surface of the forming platform under the vibration. The mixing time for each filling of the auger to the entire hopper is controlled within 5-10 seconds, and the distance between the outer surface of the auger and the side wall of the hopper is 10-25 mm; the frequency of the vibration motor is controlled within the range of 30-50 Hz; the gear shaft has 6-8 grooves, and under the rotation of the gear shaft, the material enters the grooves and flows out, and the distance between the outer surface of the gear shaft and the side wall of the hopper outlet is 0.5-2 mm; the forming box includes side plates, reinforcing plates, a bottom support, a forklift slot, and a lifting power assembly; the forming box contains four side plates to form the maintenance structure of the forming box, limiting... The powder material moves horizontally. Reinforcing plates are located on the front and rear side plates, with a cross-sectional shape that is wider at the bottom and narrower at the top. A lifting power assembly is installed on each of the left and right sides of the molding box to control the vertical movement of the molding platform. The molding platform is located inside the molding box, and the gap between the molding platform and the side plates is sealed with felt. The lifting power assembly includes a bracket, a lifting motor, a lifting screw, a lifting connector, a lifting slider, a lifting slide rail, and a lifting support. The lifting motor is located at the bottom of the side plate, with its output end pointing vertically upwards and connected to the lifting screw. Two lifting slide rails are symmetrically installed on both sides of the lifting screw via brackets. Lifting sliders are installed on the lifting slide rails, and lifting connectors are fixedly installed on the two lifting sliders. The center of the lifting connector is fixed to the lifting screw. The lifting motor drives the lifting screw to rotate, thereby controlling the lifting connector to move up and down along the lifting slide rails as the screw rotates. The lifting bracket is fixedly connected to the forming platform by bolts. Both ends of the lifting bracket protrude from the side plates of the forming box and contact the lifting connectors. Two gaps are provided on each of the left and right side plates along the height direction, allowing the connection between the lifting bracket and the forming platform to move along the gaps. The downward movement provides space for the lifting bracket to move. At this time, both ends of the lifting bracket are located above the lifting connector, and the two are in contact with each other. When the lifting connector rises, it can drive the lifting bracket to rise. The two do not need to be welded, just in contact. Lifting is achieved through contact. When not in contact, the forming box can be moved horizontally. Several horizontal connectors fix the bracket to the frame at the corresponding position. The bottom bracket of the forming box can move along the cable chain to realize the moving of the forming box into the printing and removal of the powder cleaning. The bottom of the forming box is equipped with a forklift slot. After the forming box is removed, the forklift puts the forklift into the forklift slot to remove the forming box.

2. The molding apparatus according to claim 1, characterized in that, The described inkjet printing component includes an ink supply component, an inkjet connection plate, a crossbeam module, a nozzle fixing part, a nozzle fixing plate, and a nozzle; the ink supply component uses circulating negative pressure ink supply to continuously provide ink for the nozzle automatically; the ink supply component and the nozzle fixing part are fixed to the inkjet connection plate by bolts, the lower part of the nozzle fixing part installs the nozzle fixing plate, the nozzle is embedded in the nozzle fixing plate, the bottom surface of the nozzle and the bottom surface of the nozzle fixing plate are at the same horizontal plane, the nozzle extends into the forming box, the distance from the bottom surface of the nozzle to the surface of the forming platform is 3 - 6 mm, and an array of nozzles is arranged in a "pin" shape, the overlap rate between nozzles should be 1 - 3%, and the nozzle fixing plate is connected to the nozzle fixing part by No. 3 bolts; the middle part of the inkjet connection plate is connected to the crossbeam module through a slider, and the ink supply component and the nozzle move horizontally along the horizontal slide rail of the crossbeam module under the action of the slider; both ends of the horizontal slide rail are respectively fixedly connected to a No. 4 connection plate by bolts, the outside of the No. 4 connection plate is fixed to a No. 5 connection plate, and the No. 5 connection plate is connected to the longitudinal beam module through a corresponding slider.

3. The molding apparatus according to claim 2, characterized in that, The ink droplets of the nozzle are 15 - 80 pl in size.

4. A powder bonding molding method for complex geological models, using the molding apparatus described in claim 1, the molding method comprising the following steps: (1) Establish a mathematical model of the geological model; (2) Use a slicing algorithm to slice the geological model to obtain slicing contour data; (3) Convert the slicing contour data of all layers into dot matrix data recognizable by the nozzle and transmit it to the 3D printing control system, and set the control software parameters for printing; (4) The 3D printing control system issues a data instruction for the layer to be printed to the nozzle to prepare for printing, and raises the forming platform to the highest position; (5) Start printing and perform powder dropping and powder spreading: The feeding tank sucks the powder material into it and transports it to the powder dropping and spreading component through the outlet at its bottom, and then performs powder dropping and powder spreading rolling from left to right on the forming platform. After laying one layer of powder, the powder dropping and spreading component returns to its original position to wait for instructions, and the powder laying speed is 20 - 50 seconds per layer; while spreading the powder, the 3D printing control system issues a data instruction for the next layer to the nozzle; (6) Perform inkjet printing: The inkjet printing component prints step by step from right to left, and the step width is the total effective spraying width of the array of nozzles. When printing each step width, the nozzle moves along the horizontal slide rail direction of the crossbeam module and performs inkjet printing, and only sprays ink on the model entity area to bond and cure the powder material in the entity area. After completing one layer of inkjet printing, the inkjet printing component returns to its original position to wait for instructions; (7) The forming platform descends: The forming platform of the forming box moves down a layer thickness distance, and the layer thickness is 0.1 - 0.3 mm; (8) Repeat steps (5) to (7) layer by layer to complete the production of the model; (9) Use the forming box moving component to move the forming box out of the machine frame; (10) Use the powder cleaning component to clean and recycle the unconsolidated and hardened powder in the removed forming box, and take out the finished geological model.

5. The molding method according to claim 4, characterized in that, The powder is a cement-based powder, mainly including cement and fine aggregate, and the cement is one or several of ordinary Portland cement, sulfoaluminate cement, and magnesium phosphate cement; the ink during inkjet is a water-based ink, and the water-based ink includes deionized water, viscosity modifier, solubilization stabilizer, and surface tension modifier.

6. The molding method according to claim 5, characterized in that, The molding method is used for printing adhesive 3D printing similar materials for complex geological models. The similar materials include powder materials and ink. The powder materials, by weight, include 10-40 parts of recalcined MgO, 5-30 parts of phosphate, 30-100 parts of barite powder, 8-25 parts of hemihydrate gypsum, and 50-100 parts of precision-improving components. The ink includes 3-10% viscosity modifier, 0.5-2.5% solubilizer and stabilizer, 0.1-0.8% surface tension modifier, and 0... 0.01-0.1% defoamer, 3-6% humectant, 80-97% deionized water; the viscosity modifier is at least one of PVA, polyvinylpyrrolidone (PVP), or xanthan gum; the weight ratio of ink to powder material is 0.2-0.4; the precision improving component includes PVA powder and cement clinker powder, the mass ratio of PVA powder to cement clinker powder is 1:5-1:8; the solubilizing stabilizer is at least one of 2-pyrrolidone and sodium pyrrolidone carboxylate.

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